1. Field of the Invention
This invention relates to vehicle wheel and tire technology and, more particularly, to improved wheel and tire systems for non-pneumatic tires and pneumatic, low profile tires.
2. Description of the Related Art
Most vehicles utilize wheels and tires to control the motion of the vehicle and absorb and transmit the forces associated with the vehicle's mobility. The typical wheel and tire system comprises a solid circular structure, the wheel, mounted to an axle of the vehicle. A tire, typically made of rubber, is mounted on the wheel structure at the point called the rim of the wheel. The tire is generally held in place on the wheel by a combination of the tire's inner structural support members, comprising partly of the tire bead and cord, and air pressure. Sufficient air pressure is required to maintain the proper shape of the tire and maintain sufficient friction between the tire and the rim to prevent separation of the two. The loss of air can lead to catastrophic failure of the wheel and tire structure, resulting in injury and property damage.
Several attempts have been made to reduce or eliminate this risk associated with air filled, or pneumatic tires. Several alternative solutions exist. The most common, partial solution is provided by what are called Run-Flat Tires. These tires provide additional structural elements within the tire to prevent catastrophic failure in the event of loss of air pressure. Currently, these have limitations such as speed and distance traveled after the event of air loss. Some companies have developed non-pneumatic tire and wheel combinations that utilize flexible structures such as plastic honeycomb shapes to replace the compliance, or ride softening provided by pneumatic tires. However, these solutions have several disadvantages in certain applications. The tire component of this solution is typically bonded to the compressible portion of the system. This limits the ability to replace worn tire tread as easily as it is with today's wheel and pneumatic tire structure. In addition, the dynamic compression of these solutions may not support the desired handling response and low rolling resistance. Lastly, few of these designs have shown significant weight savings, a key factor in reducing fuel and other operating costs of a vehicle. Lastly, the class of Large Load Hauling Trucks such as the Caterpillar 797 must have minimal down time and eliminating the risk of down time due to flat tires has significant value for industry.
To proliferate the use of non-pneumatic tires, a solution is required that meets or exceeds current wheel and tire performance and weight characteristics without significant additional costs. In addition, current high performance wheel and tire combinations provide performance at the cost of ride comfort. The ideal solution would also improve handling performance while improving ride comfort.